Jul 12 – 23, 2021
Europe/Berlin timezone

Muon number rescaling in simulations of air showers

Jul 14, 2021, 6:00 PM
1h 30m


Talk CRI | Cosmic Ray Indirect Discussion


Dr Dariusz Gora (Institute of Nuclear Physics Polish Academy of Science)


The number of muons in extensive air showers predicted using LHC-tuned hadronic interaction models, such as EPOS-LHC and QGSJetII-04, is smaller than observed in showers recorded by leading cosmic rays experiments. In this paper, we present a new method to derive muon rescaling factors by analyzing reconstructions of simulated showers. The z-variable used (difference of initially simulated and reconstructed total signal in detectors) is connected to the muon signal and is roughly independent of the zenith angle but depends on the mass of primary cosmic ray. The performance of the method is tested by using Monte Carlo shower simulations for the hybrid detector of the Pierre Auger Observatory. Having an individual z-value from each simulated hybrid event, the corresponding signal at 1000 m, and using a parametrization of the muon fraction in simulated showers, we can calculate the multiplicative rescaling parameters of the muon signals in the ground detector even for an individual event, and study its dependence as a function of zenith angle and the mass of primary cosmic ray. This gives a possibility not only to test/calibrate the hadronic interaction models, but also to derive the beta exponent, describing an increase of the number of muons as a function of primary energy and cosmic-ray mass. Detailed simulations show dependence of beta on hadronic interaction properties, thus the determination of this parameter is important to understand the muon deficit problem.


cosmic rays, hadronic interactions, extensive air showers

Subcategory Experimental Methods & Instrumentation

Primary author

Dr Dariusz Gora (Institute of Nuclear Physics Polish Academy of Science)


Dr Borodai Nataliia (Institute of Nuclear Physics PAN) Ralph Engel (Karlsruhe Institute of Technology (KIT)) Tanguy Pierog (Karlsruhe Institute of Technology (KIT)) Dr Jan Pekala (Institute of Nuclear Physics PAN) Dr Markus Roth (Karlsruhe Institute of Technology (KIT)) Dr Jaroslaw Stasielak (Institute of Nuclear Physics PAN) Dr Michael Unger (Karlsruhe Institute of Technology (KIT)) Dr Darko Veberic (Karlsruhe Institute of Technology (KIT)) Prof. Henryk Wilczynski (Institute of Nuclear Physics PAN)

Presentation materials